Haycock Mountain or known as Ghost Mountain is a locally prominent hill with the highest summit in

Bucks County Bucks County is a county in the Commonwealth of Pennsylvania. As of the 2020 census, the population was 646,538, making it the fourth-most populous county in Pennsylvania. Its county seat is Doylestown. The county is named after the English ...

. It rises above

Nockamixon State Park Nockamixon State Park is a Pennsylvania state park on in Bedminster and Haycock Townships in northern Bucks County, Pennsylvania, in the United States. The park is one of the most popular in southeastern Pennsylvania, with most tourists visiti ...

, in the

Delaware River The Delaware River is a major river in the Mid-Atlantic region of the United States. From the meeting of its branches in Hancock, New York, the river flows for along the borders of New York, Pennsylvania, New Jersey, and Delaware, before ...

drainage of southeastern

Pennsylvania Pennsylvania (; ( Pennsylvania Dutch: )), officially the Commonwealth of Pennsylvania, is a state spanning the Mid-Atlantic, Northeastern, Appalachian, and Great Lakes regions of the United States. It borders Delaware to its southeast, ...

. Early settlers named it simply for its "resemblance to a cock of hay."Quoted at from Haycock is covered with numerous triassic

diabase Diabase (), also called dolerite () or microgabbro, is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. Diabase dikes and sills are typically shallow intrusive bodies and often exhibit fine-grain ...

boulders, and is a

bouldering Bouldering is a form of free climbing that is performed on small rock formations or artificial rock walls without the use of ropes or harnesses. While bouldering can be done without any equipment, most climbers use climbing shoes to help se ...

destination with many established routes ranging from V0 to V10+. To the north northwest of the main peak is a secondary peak of approximately sometimes known as 'Little Haycock', and the main peak overlooks

Lake Nockamixon Lake Nockamixon is a reservoir in southeastern Pennsylvania, United States, and the largest lake in Bucks County. It is formed by a dam on Tohickon Creek and is the centerpiece of Nockamixon State Park. Swimming is not allowed in the lake, but b ...

to the southeast. Contained within the

Tohickon Creek Tohickon Creek is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map accessed April 1, 2011 tributary of the Delaware River. Located entirely in Bucks County, in southeastern Pennsylvania, it r ...

watershed Watershed is a hydrological term, which has been adopted in other fields in a more or less figurative sense. It may refer to: Hydrology * Drainage divide, the line that separates neighbouring drainage basins * Drainage basin, called a "watershe ...

, Haycock Mountain is drained by Dimple Creek to the west and Haycock Creek to the east. Since it lies within State Game Land Number 157, Haycock is used seasonally for hunting. *

Geology

Haycock Mountain was formed 200 million years ago by an

intrusion In geology, an igneous intrusion (or intrusive body or simply intrusion) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and com ...

of magma into local

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especiall ...

and

argillite :''"Argillite" may also refer to Argillite, Kentucky.'' Argillite () is a fine-grained sedimentary rock composed predominantly of indurated clay particles. Argillaceous rocks are basically lithified muds and oozes. They contain variable amounts ...

within the

Newark Basin The Newark Basin is a sediment-filled rift basin located mainly in northern New Jersey but also stretching into south-eastern Pennsylvania and southern New York. It is part of the system of Eastern North America Rift Basins. Geology Approximat ...

. As the magma cooled it became a large mass of erosion resistant

below the surface. Millions of years of weathering then stripped away overlying layers of shale and argillite to expose the durable diabase to the surface, creating Haycock mountain as it appears today.Inners, Jon D. ''Pennsylvania Trail of Geology - Nockamixon State Park, Bucks County: Rocks and Joints''. Prepared by the Bureau of Topographic and Geologic Survey for the Commonwealth of Pennsylvania Department of Conservation and Natural Resources. Last updated 2008. In addition to diabase, Haycock Mountain features a large area underlain by

hornfels Hornfels is the group name for a set of contact metamorphic rocks that have been baked and hardened by the heat of intrusive igneous masses and have been rendered massive, hard, splintery, and in some cases exceedingly tough and durable. These pro ...

, or local sedimentary rock that has been baked by the heat of the magma intrusion. The baked rock is most prominent within a few hundred feet of the intrusion, appearing as a dark gray hornfels. However, the magma's heat was extensive enough to produce maroon hornfels nearly a mile away.

References

{{Geology of the Newark Basin Climbing areas of the United States Mountains of Pennsylvania Igneous petrology of Pennsylvania Igneous intrusions Landforms of Bucks County, Pennsylvania Triassic magmatism